Automatic firearm



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W$ 9 i Q W\ E i d m F Aug. 11, 1936. F. "r. MOORE AUTOMATIC FIREARMOriginal Filed April 17, 1931 Patented Aug. 11, 1936 UNITED STATESPATENT OFFICE AUTOMATIC FIREARM Connecticut Application April 17, 1931,Serial No. 530,825 Renewed October 2, 1933 14 Claims.

The present invention is particularly applicable to automatic firearmsof the type disclosed in patents to John M. Browning No. 1,293,021 datedFebruary 4, 1919 and No. 1,628,226 dated May 10, 1927; but the inventionis not necessarily so limited.

In an automatic firearm of the type described the cartridges areautomatically supplied to the gun, as by means of a flexible belt, andif firing is discontinued before the cartridge supply is exhausted alive cartridge remains in the firing chamber of the barrel. If the gunhas been operated continuously for a substantial period of time thebarrel may be quite hot, particularly if the gun is not provided with aliquid-containing cooling mechanism. The heat of the barrel istransmitted to the cartridge in the firing chamber, with the possibleresult that the cartridge is exploded and there occurs a delayed andunexpected firing of the gun. Such delayed firingis obviously verydangerous.

In accordance with the present invention, the breech bolt, instead ofbeing in its forward position at the. conclusion. of firing, is held inits rearward position, and the construction of the gun is such that thecartridge is thus maintained in a rearward position and is preventedfrom entering the chamber of the heated barrel. When resumption offiring is desired the breech bolt may be released and permitted to moveforward in the usual way.

While my invention is particularly applicable to an automatic firearmsuch as described, I do not necessarily so limit myself, as somefeatures of the invention may be found useful in firearms of othertypes.

In the accompanying drawing I have shown the embodiment of the inventionwhich I now deem preferable, but it will be understood that the drawingis intended for illustrative purposes only and is not to be construed asdefining or limiting the scope of the invention, the claims forming apart of this specification being relied upon for that purpose.

i. the drawing:

Fig. 1 is a combined side and longitudinal sectional view. of a firearmembodying the invention.

Fig. 2 is a view similar to Fig. 1, but showing the operative parts indifferent relative positions.

Fig. 3 is a fragmentary plan view of the mechanism shownrin'Fig. 1, thetop plate of the gun being assumed to have been removed.

Fig. 4 is an enlarged fragmentary transverse sectional view taken alongthe line 4-4 of Fig. 1.

Fig. 5 is an enlarged fragmentary transverse sectional view taken alongthe line 5-5 of Fig. 1.

Referring to the drawing, i represents as an entirety the breech or maincasing of the gun which is generally rectangular in transverse section.Projecting from the casing I at the forward end is a cylindrical jacket2 which surrounds a barrel 3 having a firing chamber 4 at the rear endthereof. Located within the casing is a breech bolt 5 which is held inlocked relationship with the barrel at the time of firing, but which ismovable rearward separately from the barrel as the result of the recoilaction. A buffer is provided at 6 for limiting the rearward movement ofthe breech bolt. Following recoil the breech bolt is returned in theforward direction by a suitable means such as a reaction spring I.

The cartridges are fed to the gun by means of a flexible belt whichpasses through a transverse feed channel 8 in the forward part of thecasing I and the breech bolt 5 carries an extractor 9 which serves towithdraw a cartridge from the belt upon each rearward movement of thebreech bolt. Fig. 2 shows a cartridge C in the position which itoccupies when the breech bolt and extractor are in their rearmostpositions. It will be apparent that when the breech bolt and extractoragain move forward the cartridge C is pushed into the firing chamber 4.

The mechanism of the gun for effecting and controlling the movements ofthe breech bolt, the extractor and other parts is not shown in detail,as this mechanism does not of itself constitute any part of theinvention and is, or may be, similar to thoseshown in thebefore-mentioned patents to John M. Browning.

The breech bolt 5 carries a firing pin [0, the rear portion of which isshown in Fig. 1. This firing pin is engaged by a vertically movable searII, the sear being held in engagement with the firing pin by means of aspring if. A pivoted cocking lever l3 serves to move the firing ninrelatively. rearward during rearward movement of the breech bolt.Mounted on the casing is a trigger bar l4 which is so located as to beadapted to engage the sear II when the breech bolt and sear are in theirforward positions. I do not limit myself as concerns the exactconstruction of the trigger bar l4, but I prefer and have shown atrigger bar which is horizontally pivoted between its ends at IS, theforward end of the bar being positioned and shaped to engage the sear asalready described. The rear end of the trigger bar I4 is positioned tobe engaged by a forward extending portion of a pivoted trigger Hi. Itwill be observed that when the trigger i6 is pressed downward theforward extension thereof will rfiove upward, causing the trigger bar l4to turn in the clockwise direction and thus depress the sear H andrelease the firing pin [0. A stop I! limits the movement of the triggerbar.

It will be understood'that when it is desired to fire a. volley, thatis, a number of shots in rapid succession, the trigger I6 is depressedand kept depressed, thereby maintaining the forward end of the triggerbar l4in its lower position and in the path of the top of the sear. Thetrigger bar is provided with a cam surface at l4 which serves to depressthe sear as the breech bolt moves forward, the parts being soproportioned that the sear releases the firing pin at exactly the propertime. When firi'ng takes place the breech bolt again moves rearward toeffect the various operations which have been described, and upon thereturn forward movement firing is repeated. These operations areautomatically repeated as long as the trigger is kept depressed andcartridges are supplied.

Mounted in the breech casing near the rear thereof is a locking member i8 which is adapted to engage the breech bolt to hold it in its rearwardposition as shown in Fig. 2. This locking member or holding means ispreferably a pivoted pawl having a horizontal transverse pivotal supportat IS. The breech bolt 5 has a notch 20 therein into which the pawl l8may enter to engage and hold the breech bolt. The pawl I8 isautomatically moved into the notch 20 by gravity, but it ;will beunderstood that a spring may be added to assist this action if foundnecessary. It will be apparent that if the pawl I8 is allowed to actnormally it will engage and hold the breech bolt whenever the breechbolt is moved to its rearward position. It will be observed that thepawl 18 is positioned entirely within the casing, and is pivoted nearits forward end. The pawl extends rearward from its pivot and istherefore in compression when in engagement with the bolt. Thisconstruction gives a maximum of strength-for a given weight.

The pawl I8 is preferably relatively wide so as to have extendedengagement with the breech bolt, and it is provided with a central notch2| through which the trigger bar l4 extends. The upper edge of the rearportion of the trigger bar engages the pawl I 8, and the lower edge ofthe trigger bar engages a transverse lug 22 on the pawl. It will beobserved that the trigger bar itself together with the trigger l6,constitute manually controllable means which serve to move the lockingmember in such a way as to release the breech bolt. It will be evidentthat movement of the trigger and of the trigger bar serves to move thepawl l8 and to thus release the breech bolt, and that this same movementserves to bring the forward end of the trigger bar into position todepress the scar and release the firing pin to cause firing.

As the result of the automatic action of the gun, firing will continueso long as the trigger I6 is pressed, it being evident that the triggerbar will continue to hold the pawl It! in its upper inoperativeposition. It will further be evident that upon release of the triggerthe pawl l8 will engage the breech bolt upon its next rearward movementand will retain it in its rearward position as shown in Fig. 2. Thus thecartridge 0 is held out of the firing chamber 4 as already explained.

Preferably the pivotal axis at IQ for the pawl l8,

instead of being in fixed relationship to the casing. is relativelymovable.' The pawlis pivotally connected to the rear portion of ahorizontal rod 23, which is longitudinally movable in a housing 24secured to the casing. A spring 25 surrounds the rod 23 and tends tohold it in its rearmost position, the spring thus constituting anelement of the means for holding the breech bolt. The spring 25 servesto absorb the rebound which occurs when the breech bolt engages thebufier 6, thus eliminating the shock and vibration which would occur ifpivotal connection for the pawl l8 were fixedly and rigidly mounted. Thehousing 24 which carriesthe rod 23 is secured in the upper right handcorner of the casing by means of rivets 26, 26, and there may also beprovided a dowel washer 21 which is seated in part in a shallowcylindrical hole in the housing 24 and in part in a similar hole in thetop wall of the casing.

From the foregoing description it will be understool that the pawl 18and the parts which immediately support it are entirely additional tothe firing mechanism of the gun and are entirely independent of thefeeding mechanism thereof. The pawl serves the described purpose ofretaining the breech bolt in its retracted position at the conclusion offiring instead of allowing it to return to its forward position. Thepawl, while performing this function, does not otherwise modify theaction of the gun and does not interfere with the normal functioning ofthe firing and feeding mechanisms. The construction is such that if forany reason it is not desired to retain the breech bolt in retractedposition after firing the pawl and its associated parts can be readilyremoved from the gun independently of any part of the firing mechanism.This removal can be eifected by first removing the nut at the forwardend of the rod 23 and then withdrawing the pawl, l8, the rod 23 and thespring 25 rearward from the casing, the rear plate being first removedto permit such withdrawal.-

What I claim is:

1. In a firearm of the class described, the combination of a maincasing, a barrel, a breech bolt movable upon recoil rearward separatelyfrom the barrel, means for returning the breech bolt in the forwarddirection after recoil, cartridge feeding mechanism, manuallycontrollable firing mechanism, automatically operative means additionalto the firing mechanism for holding the breech bolt in its rearwardposition, and a device separate from the feeding mechanism and operableby the trigger of the firing mechanism for releasing the said holdingmeans.

2.'In an automatic firearm of the class described, the combination of amain casing, a barre]. a breech bolt movable upon recoil rearwardseparately from the barrel, means for returning the "breech bolt in theforward direction after recoil, cartridge feeding mechanism, firingmechanism including a manually controllable element on the casingadapted when in operative positiorT to eifect firing at the conclusionof each forward movement of the breech bolt, automati- ,cally operative.means additional to the firing .ward separately from the barrel, meansfor returning the breech bolt in the forward direction after recoil,cartridge feeding mechanism, firing mechanism,

scribed, the combination mechanism including a manually controllableelement on the casing adapted when in operative position to effectfiring at the conclusion of each forward movement of the breech bolt,automatically operative means additional to the firing mechanism andindependent of the feeding mechanism for retaining the breech bolt inits .rearward position, a device manually operable by the trigger of thefiring mechanism for holding the bolt retaining means in an inoperativeposition, and means for detachably engaging the bolt holding means andpermitting its complete removal independently of any part of mechanism.

4. In a firearm of the class described, the combination of a maincasing, a barrel, a breech bolt movable upon recoil rearward separatelyfrom the "barrel, means for returning the breech bolt in the forwarddirection after recoil, cartridge feeding mechanism, manuallycontrollable firing mechanism, and a pawl adapted to automaticallyengage a shoulder formed directly on the breech bolt to hold the saidbolt in its rearward position, the said pawl being located entirelywithin the casing and being additional to the firing mechanism andindependent of the feeding and a manually. operable device separate fromthe feeding mechanism for releasing the said pawl.

5. In an automatic firearm of the class deof a main casing, a barrel, 9,breech bolt movable upon recoil rearward separately from the barrel,means adapted to return the breech bolt in the forward direction afterrecoil, a firing pin and a sear therefor carried by the movable breechbolt, a looking member on the casing adapted to engage the breech boltto hold it in its rearward position, and a manually controllable meanson the casing serving to move the locking member to release the breechbolt and also serving to move the sear to release the firing pin whenthe bolt is in its forward .position.

6. In an automatic firearm of the class described, the combination of amain casing, a barrel, a breech bolt movable upon recoil rearwardseparately from the barrel, means adapted to return the breech bolt inthe forward direction after recoil, a firing pin and a sear thereforcarried by the movable breech bolt, a locking member. on the casingadapted to engage thebreech bolt to hold it in its rearward position,and a single manually operable member on the casing adapted to engageand move the locking member to release the breech bolt and also adaptedto engage and move the sear to release the firing pin when the bolt isin its forward position.

'7. In a firearm of the class described,,the combination of a maincasing, a barrel, a breech bolt movable upon recoil rearward separatelyfrom the barrel, means for returning the breech bolt in the forwarddirection after recoil, cartridge feeding mechanism, manuallycontrollable firing mechanism, and a pawl pivoted near. its forward endand extending rearward from its pivot and adapted to automaticallyengage a shoulder formed directly on the breech bolt to hold the saidbolt in its rearward position, the said pawl being located entirelywithin the easing and being additional to the firing mechanism andindependent of the feeding mechanism, and a manually operable deviceseparate from the feeding mechanism for releasing the said pawl.

8. In a firearm of the class described, the comthe firing thecasingadapted to bination of a main casing, a barrel, a breech boltmovable upon recoil rearward separately from the barrel, means forreturning the breech bolt in the forward direction after recoil,cartridge feeding mechanism, manually controllable firing mechanism, anda pawl adapted to automatically engage a shoulder formed directly on thebreech bolt to hold the said bolt in its rearward position, the saidpawlbeing located entirely within the casing and being additional to thefiring mechanism and independent of the feeding mechanism, a resilientmember within the casing associated with the pawl and adapted to permitthe pawl to move to absorb the shock engagement with the bolt, and amanually operable deviceseparate from the feeding mechanism forreleasing the said pawl.

9. An automatic firearm as set forth in claim 6,

wherein the manually operable memberis a lon- 10. In a firearm of theclass described, the

combination of a main casing, a barrel, a breech bolt movable uponrecoil rearward separately from the barrel, means for returning thebreech bolt in the forward direction after recoil, cartridge feedingmechanism, manually controllable firing mechanism, for holding thebreech bolt in its rearward position, the said holding means including aresilient element adapted to absorb shock, and a device manuallyoperable by the trigger of the firing mechanism for releasing the saidholding means.

11. In an automatic firearm of the class described, the combination of amain casing, a barrel, a breech bolt movable upon recoil rearwardseparately from the barrel, means for returning the breech bolt in theforward direction after recoil, cartridge feeding mechanism, firingmechanism including a manually controllable element on the casingadapted when in operative position to effect firing at the conclusion ofeach forward movement of the breech bolt, automaticallyoperative meansfor holding the breech bolt in its rearward position, the said meansincluding a resilient element adapted to absorb shock, and a devicemanually operable by the trigger of the firing mechanism formainautomatically operative means taining the holding means in aninoperative posibarrel, 9, breech bolt movable upon recoil rearwardseparately from the barrel, means adapted to return the breech bolt inthe forward direction after recoil, a firing pin and a sear thereforcarried by the movable breech bolt,a trigger bar on the casing adaptedto engage the sear to release the firing pin when the bolt is in itsforward position, a locking member adapted to engage the breech bolt tohold it in its rearward position, means for resiliently connecting thelocking member with the casing, and manually controllable means on thecasing for moving the locking member to release the breech bolt.

13. In an automatic firearm of the class described, the combination of amain casing, a barrel, a breech bolt separately from the. barrel, meansadapted to return the breech bolt in the forward direction after recoil,a firing pin and a sear therefor carrled by the movable breech bolt, atrigger bar on movable upon recoil rearward engage the sear to releasethe firing pin when the bolt is in its forward position, alongitudinally extending endwise movable rod in the casing, a springtending to move the rod rearward, a pawl pivoted to the rod and adaptedto engage the breech bolt to hold it in its rearward position, andmanually controllable means on the casing for moving the pawl to releasethe breech bolt.

14. In an automatic firearm of the class described, the combination of amain casing, a barrel, a breech bolt movable upon recoil rearwardseparately from the barrel, means adapted to return the breech bolt inthe forward direction after recoil, a firing pin and a sear therefor carried by the movable breech bolt, a trigger bar on the casing adapted toengage the sear to release the firing pin when the bolt is in itsforward position, a longitudinally extending endwise movable rod in thecasing, a spring tending to move the rod rearward, a pawl pivoted to therod and adapted to engage the breech bolt to hold it in its rearwardposition, and a manually operable longitudinally extending leverhorizontally pivoted between its ends, the rear part of the leverengaging the pawl to move it and release the breech bolt and the forwardpart of the lever engaging the sear to move it and release the firingpin.

FREDERICK T. MOORE.

